Pass plugin path around instead of redetecting

This is now set only once at the top level. This is needed for the
chainloading to work because we'll need to set the path when we create
the bridge.

src/common/linking.h

@@ -19,7 +19,7 @@
 // This header is completely standalone so the chainloading libraries can
 // retrieve their file path without pulling in a lot of additional dependencies
 
-#include <string>
+#include <ghc/filesystem.hpp>
 
 /**
  * Return a path to this `.so` file. This can be used to find out from where
@@ -29,4 +29,4 @@
  * library using the provided exported functions since they can't detect the
  * path themselves.
  */
-std::string get_this_file_location();
+ghc::filesystem::path get_this_file_location();